In one aspect, this invention relates to random or dumped packings. In another aspect, this invention relates to a method of making such packings. In a further aspect, this invention relates to a column containing such packings. In a still further aspect, this invention relates to the use of a column containing such packings.
Column packings such as are used in the chemical and petrochemical industries are generally divided into three classes, namely
a) Random or Dumped Packings:
These are discrete pieces of packing of a specific geometrical shape, which are dumped or randomly packed into the column shell.
b) Structured or Systematically Arranged Packings:
These are crimped layers of wire mesh or corrugated sheets. Sections of these packings are stacked in the column.
c) Grids:
These are also systematically arranged packings, but instead of wire-mesh or corrugated sheets, these grid-packings use an open-lattice structure.
The field of this invention is random or dump packings. For this application, the earliest engineers used tree barks and round-shape pebbles as dump packing materials for their chemical processing industries (CPI). There are three generations of evolution in random packings:
The first generation of random packing saw use from 1907 to the 1950s. Two basic simple shapes were widely used; namely the Raschig(copyright) ring (first patented by Dr. Raschig in Germany in 1907) and the Berl(copyright) saddle that became the ancestors of modern random packings. These packings have all been superseded by today""s modern packings, and are seldom used in today""s CPI.
The second generation of random packings were developed from the late 1950xe2x80x2s to the early 1970xe2x80x2s. During this period, there were two popular geometrical shapes, namely the Pall(copyright) ring, which evolved from the Raschig(copyright) ring, and the Intalox(copyright) saddle, which evolved from the Berl saddle. The second generation packings are still popular and extensively used in modern CPI today.
The third generation random packings have seen use since the mid 1970xe2x80x2s. Third generation packing has produced a multitude of popular geometries, most of which evolved from the Pall(copyright) ring and Intalox(copyright) saddle, both in metallic and in plastic materials. Popular brand names are as follows: Intalox(copyright) Metal Tower Packing (IMTP(copyright)), marketed by Norton Company, Cascade(copyright) Mini-Rings (CMR(copyright) and CMR(copyright) Turbo, both marketed by Glitsch, Inc., Chempak(copyright) or Levapak (LVK(copyright) available in metal from Nuttering Engineering Corporation and in plastic and other nonmetals from Chemetics International, Nutter Rings(copyright), available in metal and plastic, marketed by Nutter Engineering Corporation, HcKp(copyright), marketed by Koch Engineering Company, Inc., Fleximax(copyright), available in metal from Koch Engineering Company, Inc., Hiflow(copyright) ring, available in metal, plastic and ceramics from Rauschert Industries, Inc., Jaeger Tri-Packs(copyright), available in metal as Metal Jaeger Top-Pak(copyright) and plastic as Hackette(copyright) from Jaeger Products, Inc., NOR PAC(copyright) (NSW) rings, available in plastic from Nutter Engineering Corporation and from Jaeger Products, Inc., Intalox(copyright) Snowflake(copyright) packing, available in plastic from Norton Company, LANPAC(copyright), available in plastic from Lantec Products, Inc., IMPAC(copyright), available in metal and plastic from Lantec Product, Inc., VSP(copyright), available from Jaeger Products, Inc., and Interpack(copyright), available from Jaeger Products, Inc., Others packings, for example Tellerette(copyright), Maspac(copyright), Dinpak(copyright), SuperTorus(copyright) Saddle, Hiflow(copyright) Saddle, Ralu(copyright) Ring, ENVIPAC(copyright), Super Levapak (S-LVK(copyright)) etc. are also widely used in modern CPI.
One of the leading challenges for improving the known art of random packings is to increase in the total available surface areas of the packing materials.
By increasing the surface area of packings, more liquid loading (in terms of gallons per minute per square feet) can be achieved, which in return can improve the reaction efficiency at the wetting surface of a gas stream and a liquid stream, as in the example of a toxic gas scrubber process, or for liquid feed streams in a distillation column operation.
Raschig rings, which started the age for first generation of random packings, are much more consistent and provide more predictable end results than tree barks and pebble stones. With increases in surface areas, then came the Bert Saddle packings, which outperform the Raschig rings in fluid flow hydrodynamics and performance efficiencies.
Up until the early 1970s, the second generation random packings came with significant efficiency improvement over the earlier first generation packings, simply by changing the geometrical shape of both the Raschig ring and Berl saddle to provide an increase in surface area over the previous ones. The two main representatives of the second-generation random packings are the Pall(copyright) ring and the Super Intalox(copyright) saddle.
The third generation random packings approximately started from early 1970s till today. The CPI saw a stream of constant newer random packings being introduced on yearly basis. Every time a new random packing enters the market stage, we see a clear sign that each entry of this newer random packing has tried to outdo its competitors by introducing a more intricate network of ribs, rods, struts and pointed fingers, mostly all cross-linked and uniformly spaced throughout the open-structural framework, with the ultimate goal of increasing in the surface area of the random packing, thus increase in performance and efficiency.
On the other hand, there is a common xe2x80x9cdarkxe2x80x9d side in many of today""s third generation random packings. In order to increase the surface area, the packing materials become more complex in geometrical shapes, resulting in more individual breakage, less structural rigidity, and more interlocking inside a CPI column. The dilemma facing today""s random packings is how to significantly increase the surface area without sacrificing the structural integrity of the individual random packing.
No matter how smart a design engineer, carving out more space to produce more surface area from a solid spherical or cylindrical material like metals or plastics will always weaken structural integrity. The more complex the geometrical shapes, the more surface area and the damage to the structural integrity of the random packings.
It is an object of this invention to provide higher surface area for a column packing without loss of integrity.
In one embodiment of the invention, there is provided a packing element for a column. The element comprises a first plurality of parallel plates and a second plurality of parallel plates. The first plurality of parallel plates have peripheries which enable them to be accommodated within a sphere. The second plurality of parallel plates interconnect the first plurality of parallel plates and are positioned normally to the first plurality of parallel plates. The second plurality of parallel plates have peripheries which enable them to also be accommodated within the sphere.
Preferably, the packing element is housed in a cage element to form a packing assembly. The cage possesses a crush strength sufficient to withstand crushing forces to be encountered when the packing assembly is deployed in a column. The packing element is positioned in the cage element to provide the packing assembly with more than half of its surface area. The cage protects the packing element.
In use, a multiplicity of the packing assemblies are positioned in a chemical process column having an upper end and a lower end. Preferably, the packing assemblies each comprise a packing body or element surrounded by a protective cage assembly or element. More preferably, the packing assemblies are randomly dumped into the column. A liquid stream is introduced into the upper end of a column and flowed downwardly through the packing in the column. A gas stream is introduced into the lower end of the column and flowed upwardly through the packing in the column for countercurrent contact with the liquid stream. Where the packing element of the packing assembly fits loosely in the cage element and can rotate in the cage element in response to impact by fluid to reduce the pressure drop through the bed, the individual assemblies, will, over time, orient in the column.